Hydrocarbon conversion process

ABSTRACT

Provided is a process for producing gasoline having a high octane number or aromatic hydrocarbons by contacting a feed stock containing at least one aliphatic hydrocarbon having 1 to 12 carbon atoms with a catalyst at an elevated temperature said catalyst comprising a zeolite and a fluorine compound, and optionally Group Ib, IIb, IIIa, VI, VIIb or VIII metal in the Periodic Table.

BACKGROUND OF THE INVENTION

The present invention relates to a hydrocarbon conversion and moreparticularly to a process for producing gasolin having a high octanenumber and/or aromatic hydrocarbons by contacting a feed stockcontaining aliphatic hydrocarbon(s) of 1 to 12 carbon atoms with azeolite catalyst at an elevated temperature.

In petroleum refineries, cracked gases comprising C₁ to C₄ paraffinsand/or olefins are by-produced in large quantities from fluid catalyticcracking unit, thermal cracking unit or hydrocracking unit. These gasesare usually consumed as fuel in those refineries or for domestic use.But, the development of use having an enhanced added value is desired.

Further, in producing ethylene and propylene by subjecting a petroleumdistillate such as naphtha to a thermal cracking treatment in thepresence of steam, a considerable amount of thermal-cracked gasoline isproduced. Since this thermal-cracked gasoline contains a large amount ofdiolefins, it tends to polymerize during storage and form a large amountof gum, so it is desired to develop an effective method for removing thediolefins.

On the other hand, light straight-run naphtha from a distillation columnis usually employed as a blend with gasoline, but a novel aromatizationmethod has been desired because of a low octane number. Medium and heavynaphtha distillate from a distillation column is introduced into areforming unit to produce reformed gasoline. But, the reformed gasolinecontains large amounts of saturated aliphatic hydrocarbons, includingthose of C₅ and C₆, which are a cause of reduced octane number ofproducts.

As a method for effectively utilizing C₂ to C₅ olefin gas contained inthe above cracked gas, there is a polymer gasoline method or OTGreaction (Olefin-to-Gasoline), in which the said olefin gas islow-polymerized for conversion into gasoline. A solid acid is usuallyemployed as catalyst, typical of which is a catalyst comprisingdiatomaceous earth or quartz sand and phosphoric acid adsorptivelyimmobilized thereon. In this case, it is necessary that the operationfor adsorptively immobilizing phosphoric acid should be done frequentlybecause phosphoric acid is washed away quickly.

It is also known to use zeolite as catalyst. Especially, zeolites withpores each comprising a ten- or twelve-membered oxygen ring, such asZSM-5, ZSM-11, mordenite, Y type zeolite and faujasite, exhibit afterdealkalization a superior OTG reaction activity. For example, it isdisclosed in Japanese Patent Laid Open No. 103292/1981 that aromatichydrocarbons can be obtained in high yield by using as catalyst azeolite having a high silica/alumina ratio such as ZSM-5 or ZSM-11. Andit is disclosed in Japanese Patent Laid Open No. 24835/1979 that suchzeolite catalyst is also effective for the aromatization of diolefinscontained in thermal-cracked gasoline. Further, it is disclosed inJapanese Patent Publication No. 42639/1981 and Laid Open No. 93918/1982that catalysts comprising such zeolites and various metals supportedthereon permit conversion of not only unsaturated aliphatic hydrocarbonsbut also saturated aliphatic hydrocarbons into aromatic hydrocarbons.

However, in OTG reaction and aromatization using those zeolitecatalysts, there occurs a rapid deterioration of catalytic activitycaused by deposition of coke, so it is necessary to frequently performthe operation for catalyst regeneration by air calcination.

SUMMARY OF THE INVENTION

It is an object of the present invention to eliminate theabove-mentioned drawbacks of the prior art.

It is another object of the present invention to provide a process forobtaining gasoline having a high octane number and/or aromatichydrocarbons in high yield from a feed stock containing aliphatichydrocarbons of 1 to 12 carbon atoms by the use of a catalyst having along life and causing little deposition of coke.

The present invention resides in a process for producing reformedgasoline and/or aromatic hydrocarbons by contacting a feed stockcontaining at least one aliphatic hydrocarbon of 1 to 12 carbon atomswith a catalyst comprising zeolite and a fluorine compound at anelevated temperature.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The zeolite used in the present invention is a natural or syntheticzeolite having a crystal pore diameter of 3 to 9 Å and a silica/aluminamol ratio of 1 to 500, preferably 1 to 100. Examples are faujasite,gmelinite, zeolite L, mordenite, zeolite Ω, zeolite X, zeolite Y,ferrierite, ZSM-5, ZSM-11 and clinoptilolite. Particularly, ZSM-5,ZSM-11, mordenite, zeolite Y, faujasite and transition metal silicatesare preferred.

The transition metal silicates indicate zeolites having an X-raydiffraction pattern similar to that of ZSM-5 or ZSM-11 and containing atransition metal as one constituent. Employed preferably are thosecontaining one or more transition metals selected from Fe, Cr, V, Bi,Ti, B, Be and Ga.

The OTG or aromatization reaction partially involves an acid catalystreaction. Therefore, in using the zeolite as catalyst in the process ofthe present invention, it is preferable that the alkali proportion inthe zeolite be decreased in advance by dealkalization using an acid oran ammonium salt.

The dealkalizing ratio is preferably not less than 50 mol %, morepreferably not less than 90 mol %, of the alkali metal or alkaline earthmetal contained in the zeolite. As examples of a dealkalizing agent,mention may be made of mineral acids such as hydrochloric, sulfuric,nitric and phosphoric acids, water-soluble organic acids such as formic,acetic and malic acids, as well as ammonium ion-containing salts such asammonium chloride and ammonium nitrate. Above all, hydrochloric acid,sulfuric acid, ammonium chloride and ammonium nitrate are preferred.These acids or salts may be used each alone or in combination and areused in the form of an aqueous solution. In this case, the acidconcentration is preferably in the range of 1 to 30%, preferably 5 to15%, although these concentrations differ according to treatingconditions.

The treating temperature may be room temperature, but heating to80°-100° C. is preferred in order to shorten the treating time. Thetreating time is preferably 5 hours to 3 days although it depends ontemperature.

The fluorine compound used in the present invention is an inorganiccompound comprising fluorine and a metal or a non-metallic element.Examples are aluminum fluoride, ammonium fluoride, magnesium fluoride,barium fluoride, zirconium fluoride, phosphorus fluoride, boronfluoride, zinc fluoride, gallium fluoride, cadmium fluoride, nickelfluoride, chromium fluoride, tin fluoride, copper fluoride, silverfluoride, rhenium fluoride, manganese fluoride, molybdenum fluoride,selenium fluoride, tellurium fluoride, tungsten fluoride, lanthanumfluoride, cerium fluoride, titanium fluoride and calcium fluoride.Organic compounds of fluorine are also employable such as, for example,Freon 11, Freon 12, Freon 14, Freon 114 and Freon C 318 (trade name,manufactured by Du Pont). Among these fluorine compounds, particularlypreferred are aluminum fluoride, ammonium fluoride, magnesium fluoride,zirconium fluoride, phosphorus fluoride, boron fluoride and Freon 12.

Preferred examples of aluminum fluoride are hydrate aluminumtrifluorides and basic aluminum fluorides, such as α-AlF₃ ·3H₂ O, β-AlF₃·3H₂ O as well as aluminum fluorides obtained by calcining thosehydrated aluminum fluorides at a temperature not higher than 700° C.,preferably 200° to 500° C. Also effective are aluminum fluoridesobtained by passing an excess amount of anhydrous hydrogen fluoridethrough a reaction tube charged with alumina, aluminum hydroxide or amixture thereof at a temperature of 200° to 500° C., or passing anexcess amount of anhydrous hydrogen fluoride through a reaction tubecharged with aluminum chloride at a temperature of 20° to 400° C. Inpreparing these aluminum fluorides as a catalyst component used in theprocess of the present invention, a pure preparation thereof is notneeded; in other words, a mixture thereof suffices.

Thus, the catalyst used in the present invention contains zeolite andthe fluorine compounds as essential components. But, it is desirable forthe aromatization that these components be combined with at least onemetal selected from Group Ib, IIb, IIIa, VI, VIIb and VIII metals in thePeriodic Table. Examples are Cu, Ag and Au as Group Ib metals, Zn and Cdas Group IIb metals, Al, Ga, In and Tl as Group IIIa metals, Cr, Mo, W,Se and Te as Group VI metals, Mn, Tc and Re as Group VIIb metals, andFe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt as Group VIII metals. Particularlypreferred are Cu, Ag, Zn, Cd, Ga, Cr, W, Se, Te, Re, Co, Ni, Pd, Ir andPt.

The composition of the catalyst used in the process of the presentinvention is usually as follows although it differs according toreaction conditions: zeolite 20-99 wt. %, preferably 40-90 wt. %fluorine compound 1-80 wt. %, preferably 5-40 wt. %, metal (if used)0.1-30 wt. %, preferably 1-20 wt. %.

The catalyst used in the process of the present invention can beprepared by any suitable method. The catalyst not containing themetallic element can be obtained by adding the fluorine compound tozeolite which has been dealkalized or not dealkalized, forming theresulting mixture into a suitable shape such as a powdered or granular(1-5 mm dia.) shape by, for example, compression molding, followed bycalcining at 100°-700 ° C., preferably 300°-600° C., for 0.5 to 100hours, preferably 1 to 8 hours.

On the other hand, the catalyst containing the metallic element can beobtained by adding the metallic element to zeolite which has beensubjected or not subjected to dealkalization, in a conventional mannersuch as an ion exchange method or an impregnation method.

The metallic element is added to zeolite by first dissolving in asuitable solvent, e.g. water, in the form of a salt with mineral acid ororganic acid, a chelate compound, a complex salt or an oxide and thencontacting with the zeolite. In this case, the metal concentration ispreferably in the range of 0.1 to 1.0 mol/l although it differsdepending on the kind of metal and treating conditions.

The treating temperature may be room temperature in the case of an ionexchange method, but heating to 80°-100° C. is desirable to shorten theexchange time. Where the impregnation method is adopted, the treatingtemperature is preferably near the boiling point of the solvent. Thetreating time is preferably 30 minutes to 3 days although it depends ontemperature.

The metallic element may be present as a metal oxide or a metal cation(in the case where the cation in the zeolite is replaced by the saidmetal cation) or as metal.

The zeolite thus mixed with the metallic element is then dried at atemperature usually in the range of 50° to 200° C., preferably 100° to150° C., for 0.5 to 100 hours, preferably 1 to 8 hours, then mixed withthe fluorine compound, then the mixture is formed into a suitable shapesuch as a powdered or granular (1-5 mm dia.) shape by, for example,compression molding, followed by calcining at 100°-700° C., preferably300°-600° C., for 0.5 to 100 hours, preferably 1 to 8 hours. Theaddition of the metallic element to the zeolite may be done after theaddition of the fluorine compound and calcination. The calcinationusually is carried out in air. But, of course, it may be effected in aninert gas such as nitrogen or carbon dioxide, or hydrogen gas.

The feed stock used in the present invention contains as an essentialcomponent at least one aliphatic hydrocarbon having 1 to 12 carbonatoms. It may contain a mixture of such aliphatic hydrocarbons.Particularly, C₂ to C₄ aliphatic hydrocarbons or mixtures thereof arepreferred. Light straight-run naphtha or reformed naphtha distillate orthermal-cracked gasoline contains a considerable amount of aliphatichydrocarbons and is a desirable feed stock. The feed stock may containaromatic hydrocarbons provided their content is usually not higher than30% and not higher than 70% in the case of reformed naphtha.

The reaction in the present invention is carried out using the feedstock alone or in a gaseous atmosphere of, for example, nitrogen, steam,hydrogen or carbon dioxide. Preferably, it is effected in a hydrogen gasatmosphere. Hydrogen is effective mainly for reducing the amount ofcarbonaceous material deposited.

The amount of hydrogen to be added relative to the starting hydrocarbonis not specially limited, but not greater than 1:50 as the startinghydrocarbon:hydrogen mol ratio is sufficient, and preferably in therange of 1:1 to 1:5. Part of the hydrogen produced by the reaction isalso employable for this purpose.

The reaction pressure is preferably in the range of 1 to 100 atm, morepreferably 5 to 20 atm, and the reaction temperature is preferably inthe range of 250° to 700° C., more preferably 400° to 600° C.

The starting gas feed rate per unit weight of the catalyst, WHSV (g-feedgas/g-cat.hr), is not specially limited, but in order to attain a highconversion, it is preferably not higher than 10, more preferably in therange of 0.5 to 2.0.

The reaction may be performed using a known method such as a fixed bedor a fluidized bed, for example.

[Effect of the Invention]

The catalyst used in the present invention has a long life and causeslittle deposition of coke. By using such catalyst, aromatic hydrocarbonscan be obtained in high yield. Consequently, it is possible to obtaingasoline of a high octane number from the inexpensive feed stock.

The following examples are given to further illustrate the presentinvention.

EXAMPLE 1

Sodium form of ZSM-5 was calcined at 500° C. for 5 hours, then treatedwith 2N hydrochloric acid at 90°-100° C. for 5 hours, then washed withwater thoroughly and thereafter dried at 120° C. for 5 hours to obtain adealkalized ZSM-5 (catalyst 1).

20 wt. % of aluminum trifluoride was added and mixed to the aboveacid-treated catalyst 1, then the mixture was compression-molded into3×4 mm dia. pellets, which were then calcined at 500° C. for 8 hours(catalyst 2).

Using 2.0 g. of each catalyst thus obtained, a life test of OTG reactionwas made at 300° C., a hydrogen flow rate of 4.2 l/hr, a feed gas flowrate of 2.0 g/hr, hence a hydrogen to feed gas mol ratio of 3.0, WHSV of1 hr⁻¹, at atmospheric pressure. As used herein, C₃ ' designates a C₃olefin and C₄ ' designates a C₄ olefin. Results are as set out in Table1 below.

                  TABLE 1                                                         ______________________________________                                                        Feed   Catalyst 1 Catalyst 2                                  Catalyst        Gas    (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      7.0    215.0   7.0  220.0                                  C.sub.3.sup.-  + C.sub.4.sup.-  Conversion (%)                                                   95.2   72.0    76.6 74.3                                   Distribution                                                                            C.sub.1 -C.sub.2                                                                        --     2.5  1.8   2.8  2.5                                of Resulting                                                                            C.sub.3   3.1    36.5 7.1   8.7  8.5                                Hydrocarbons                                                                            C.sub.3.sup.-                                                                           1.4    1.2  6.1   5.2  5.4                                (wt. %)   C.sub.4   57.1   34.4 59.6  54.4 53.8                                         C.sub.4.sup.-                                                                           38.3   0.7  5.0   4.1  4.8                                          C.sub.5.sup.+                                                                           0.1    4.3  12.2  10.7 11.7                                         Aliphatics                                                                    Aromatics --     20.4 8.2   14.1 13.3                                         Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                                 24.7   20.4    24.8 25.0                                   ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

The C₃ '+C₄ ' conversion and the distribution of the resultinghydrocarbons, just after the run (after 7 hours), are here comparedbetween catalyst 1 and 2. The C₃ '+C₄ ' conversion in the use ofcatalyst 1 is 95%, while it is as low as 77% in the use of catalyst 2.Catalyst 1 is much higher in initial activity.

However, the C₅ ⁺ gasoline yield in the use of catalyst 1 and that inthe use of catalyst 2 both are about 25 wt. % and thus almost equal toeach other. Therefore, catalyst 2 is superior in the selectivity togasoline.

Now, a comparison is here made between both catalysts with respect toactivity and selectivity after the lapse of about 200 hours. Theactivity of catalyst 1 lowers gradually, and the C₃ ' +C₄ conversionafter 215 hours is as low as 72%. On the other hand, the activity ofcatalyst 2 changes little, and the C₃ '+C₄ ' conversion after 220 hoursis 74.3%. Also as to C₅ ⁺ gasoline yield, it lowers to about 20% in theuse of catalyst 1, while a high value of 25% is held in the use ofcatalyst 2.

From the above it is seen that catalyst 2 has a long life and exhibits asuperior selectivity to C₅ ⁺ gasoline.

EXAMPLE 2

Sodium form of a synthetic mordenite was calcined at 500° C. for 5hours, then treated with 2N hydrochloric acid at 90°-100° C. for 5hours, then washed with water thoroughly and thereafter dried at 120° C.for 5 hours to obtain a dealkalized mordenite (catalyst 3).

20 wt. % of aluminum trifluoride was added and mixed to the aboveacid-treated catalyst 3, then the mixture was formed into 3×4 mm dia.pellets, which were then calcined at 500° C. for 8 hours (catalyst 4).

Using 2.0 g. of each catalyst thus obtained, a life test of OTG reactionwas made under the same reaction conditions as in Example 1. Results areas set out in Table 2 below.

                  TABLE 2                                                         ______________________________________                                                        Feed   Catalyst 3 Catalyst 4                                  Catalyst        Gas    (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      1.0    5.0     1.0  100.0                                  C.sub.3.sup.-  + C.sub.4.sup.-  Conversion (%)                                                   89.4   53.0    72.3 71.5                                   Distribution                                                                            C.sub.1 -C.sub.2                                                                        --     4.9  3.5   3.9  3.7                                of Resulting                                                                            C.sub.3   3.1    37.4 5.3   17.3 16.8                               Hydrocarbons                                                                            C.sub.3.sup.-                                                                           1.4    2.7  9.8   6.2  6.0                                (wt. %)   C.sub.4   57.1   36.2 58.5  48.8 48.4                                         C.sub.4.sup.-                                                                           38.3   1.5  8.9   4.8  5.3                                          C.sub.5.sup.+                                                                           0.1    3.0  8.4   12.4 13.5                                         Aliphatics                                                                    Aromatics --     14.3 5.6   6.6  6.3                                          Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                                 17.3   14.0    19.0 19.8                                   ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

From the above results it is seen that the catalyst 4 treated withaluminum trifluoride has a high selectivity to C₅ ⁺ gasoline and a longlife as compared with untreated catalyst 3.

EXAMPLE 3

Sodium form of Y type zeolite was calcined at 500° C. for 5 hours, thentreated with 2N hydrochloric acid at 90°-100° C. for 5 hours, thenwashed with water thoroughly and thereafter dried at 120° C. for 5 hoursto obtain a dealkalized Y type zeolite (catalyst 5).

20 wt. % of aluminum trifluoride was added and mixed to the aboveacid-treated catalyst 5 and the mixture was formed into 3×4 mm dia.pellets, which were then calcined at 500° C. for 8 hours (catalyst 6).

Using 2.0 g. of each catalyst thus obtained, a life test of OTG reactionwas made under the same conditions as in Example 1. Results are as setforth in Table 3 below.

                  TABLE 3                                                         ______________________________________                                                        Feed   Catalyst 5 Catalyst 6                                  Catalyst        Gas    (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      2.0    4.0     2.0  120.0                                  C.sub.3.sup.-  + C.sub.4.sup.-  Conversion (%)                                                   85.1   66.0    69.3 68.8                                   Distribution                                                                            C.sub.1 -C.sub.2                                                                        --     4.5  3.6   3.5  3.3                                of Resulting                                                                            C.sub.3   3.1    31.3 15.4  16.6 15.9                               Hydrocarbons                                                                            C.sub.3.sup.-                                                                           1.4    3.5  7.0   6.9  6.9                                (wt. %)   C.sub.4   57.1   40.8 53.2  46.0 46.1                                         C.sub.4.sup.-                                                                           38.3   2.4  6.5   5.3  5.5                                          C.sub.5.sup.+                                                                           0.1    3.5  8.1   14.5 15.3                                         Aliphatics                                                                    Aromatics --     14.0 6.2   7.2  7.0                                          Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                                 17.5   14.3    21.7 22.3                                   ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

From the above results it is seen that the catalyst 6 treated withaluminum trifluoride has a high selectivity to C₅ ⁺ gasoline and a longlife as compared with untreated catalyst 5.

EXAMPLE 4

Sodium form of ZSM-5 having an SiO₂ /Al₂ O₃ ratio of 80 was calcined at500° C. for 5 hours, then treated with 2N hydrochloric acid at 90°-100°C. for 5 hours, then washed with water thoroughly and thereafter driedat 120° C. for 5 hours to obtain a dealkalized ZSM-5 (catalyst 7). Then,the zeolite was immersed in 3 mol/l of an aqueous ZnCl₂ solution,evaporated to dryness and calcined at 120° C. for 5 hours and further at500° C. for 8 hours to obtain a dealkalized 5 wt. % Zn-supported ZSM-5(catalyst 8).

On the other hand, 10 wt. % of zinc fluoride was added and mixed to thecatalyst 7 and the resultant mixture was formed into 3×4 mm dia.pellets, by compression molding, which were then calcined at 500° C. for8 hours (catalyst 9).

Using 2.0 g. of each of the catalysts 8 and 9 thus obtained, activityand life were evaluated under the conditions of temperature 520° C.,hydrogen flow rate 4.2 l/hr, feed butane-butene gas flow rate 2.0 g/hr,hence hydrogen to feed gas mol ratio 3.0, WHSV=1 hr⁻¹, at atmosphericpressure. Results are as set forth in Table 4 below.

                  TABLE 4                                                         ______________________________________                                                        Feed   Catalyst 8 Catalyst 9                                  Catalyst        Gas    (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      5.0    200.0   5.0  200.0                                  C.sub.4 + C.sub.4.sup.-  Conversion (%)                                                          79.5   37.9    73.8 60.0                                   Distribution                                                                            C.sub.1 -C.sub.2                                                                        --     18.4 5.9   15.3 10.5                               of Resulting                                                                            C.sub.3   3.1    15.9 3.2   9.1  8.8                                Hydrocarbons                                                                            C.sub.3.sup.-                                                                           1.4    3.2  15.8  5.1  7.6                                (wt. %)   C.sub.4   57.1   16.6 48.3  21.2 33.5                                         C.sub.4.sup.-                                                                           38.3   3.0  11.0  3.8  4.7                                          C.sub.5.sup.+                                                                           0.1    0.6  5.6   1.2  3.0                                          Aliphatics                                                                    Aromatics 0.0    42.4 10.7  44.1 32.0                                         Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                              0.1    43.0   16.3  45.3 35.0                                 ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

From the above results it is seen that the catalyst 9 treated with zincfluoride affords high C₅ ⁺ gasoline yield and aromatics yield and has along life as compared with the catalyst 8 impregnated with zinc.

EXAMPLE 5

Sodium form of ZSM-5 having an SiO₂ /Al₂ O₃ ratio of 28 was calcined at500° C. for 5 hours, then treated with 2N hydrochloric acid at 90°-100°C. for 5 hours, then washed with water thoroughly and thereafter driedat 120° C. for 5 hours to obtain a dealkalized ZSM-5 (catalyst 10).

Then catalyst 10 was immersed in 2 mol/l of an aqueous GaCl₃ solution,evaporated to dryness and calcined at 120° C. for 5 hours and further at500° C. for 8 hours to obtain a dealkalized 4 wt. % Ga-supported ZSM-5(catalyst 11).

On the other hand, 10 wt. % of gallium trifluoride was added and mixedto catalyst 10 and the resultant mixture was compression-molded into 3×4mm dia. pellets, which were calcined at 500° C. for 8 hours (catalyst12).

Using 2.0 g. of each of the thus-obtained catalysts 11 and 12, activityand life were evaluated under the conditions of temperature 550° C.,hydrogen flow rate 4.2 l/hr, feed B-B' gas flow rate 2.0 g/hr, hencehydrogen to feed gas mol ratio 3.0, WHSV=1 hr⁻¹, at atmosphericpressure. Results are as set forth in Table 5 below.

                  TABLE 5                                                         ______________________________________                                                        Feed   Catalyst 11                                                                              Catalyst 12                                 Catalyst        Gas    (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      5.0    200.0   5.0  200.0                                  C.sub.4 + C.sub.4.sup.-  Conversion (%)                                                          87.4   36.0    81.2 57.0                                   Distribution                                                                            C.sub.1 -C.sub.2                                                                        --     19.1 8.0   15.9 12.1                               of Resulting                                                                            C.sub.3   3.1    16.6 6.9   13.6 10.5                               Hydrocarbons                                                                            C.sub.3.sup.-                                                                           1.4    3.1  1.4   2.9  2.1                                (wt. %)   C.sub.4   57.1   10.3 49.8  15.2 35.8                                         C.sub.4.sup.-                                                                           38.3   1.8  11.3  2.7  5.2                                          C.sub.5.sup.+                                                                           0.1    0.5  0.2   0.5  0.4                                          Aliphatics                                                                    Aromatics 0.0    48.6 22.4  49.3 34.0                                         Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                              0.1    49.1   22.6  49.8 34.4                                 ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

From the above results it is seen that the catalyst 12 treated withgallium trifluoride affords high C₅ ⁺ gasoline yield and aromatics yieldand has a long life as compared with the catalyst 11 impregnated withgallium.

EXAMPLE 6

Sodium form of ZSM-5 having an SiO₂ /Al₂ O₃ ratio of 48 was calcined at500° C. for 5 hours, then treated with 2N hydrochloric acid at 90°-100°C. for 5 hours, then washed with water thoroughly and thereafter driedat 120° C. for 5 hours to obtain a dealkalized ZSM-5 (catalyst 13).

The catalyst 13 was immersed in 3 mol/l of an aqueous CdCl₂ solution,evaporated to dryness and then calcined at 120° C. for 5 hours andfurther at 500° C. for 8 hours to obtain a dealkalized 3 wt. %Cd-supported ZSM-5 (catalyst 14).

On the other hand, 4 wt. % of cadmium fluoride was added and mixed tocatalyst 13 and the resultant mixture was compression-molded into 3×4 mmdia. pellets, which were calcined at 500° C. for 8 hours (catalyst 15).

Using 2.0 g. of each of the catalysts 14 and 15 thus obtained, activityand life were evaluated under the conditions of temperature 550° C.,hydrogen flow rate 4.2 l/hr, feed butane gas flow rate 2.0 g/hr, hencehydrogen to feed gas mol ratio 3.0, WHSV=1 hr⁻¹ at atmospheric pressure.Results are as set forth in Table 6 below.

                  TABLE 6                                                         ______________________________________                                                        Feed    Catalyst 14                                                                              Catalyst 15                                Catalyst        Butane  (Comp. Ex.)                                                                              (Example)                                  ______________________________________                                        Run Time (hr)           5.0    70.0  5.0  70.0                                Conversion (%)  26.0    45.2   20.3  43.9 35.7                                Distribution                                                                            C.sub.1 -C.sub.2                                                                        --      13.1 5.0   10.4 5.5                               of Resulting                                                                            C.sub.3   --      7.8  3.0   6.6  6.1                               Hydrocarbons                                                                            C.sub.4   100.0   54.8 79.7  56.1 64.3                              (wt. %)   C.sub.5.sup.+                                                                           --      0.3  0.2   0.4  0.7                                         Aliphatics                                                                    Aromatics --      24.1 12.1  26.4 23.4                                        Total     100.0   100.0                                                                              100.0 100.0                                                                              100.0                             C.sub.5.sup.+  Gasoline* (wt. %)                                                                  24.4   12.3    26.8 24.1                                  ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

Reference to the above results shows that the catalyst 15 treated withcadmium fluoride affords high C₅ ⁺ gasoline yield and aromatics yieldand has a long life as compared with the catalyst impregnated withcadmium.

EXAMPLE 7

Using the same catalysts 8 and 9 as in Example 4, catalyst activity andlife in an aromatization reaction of n-hexane were evaluated under theconditions of temperature 480° C., hydrogen flow rate 3.6 l/hr, feedrate 2.0 g/hr, WHSV=1 hr⁻¹, at atmospheric pressure. Results are as setforth in Table 7 below.

                  TABLE 7                                                         ______________________________________                                                        Feed   Catalyst 8 Catalyst 9                                  Catalyst        n-C.sub.6                                                                            (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      20.0   250.0   20.0 250.0                                  Conversion (%)     95.0   65.0    87.7 71.3                                   Distribution                                                                            C.sub.1 -C.sub.2 24.7 3.6   12.2 9.2                                of Resulting                                                                            C.sub.3          24.3 10.2  15.6 11.9                               Hydrocarbons                                                                            C.sub.4          2.5  9.2   7.2  5.3                                (wt. %)   C.sub.5.sup.+                                                                           100.0  6.5  58.2  25.4 41.0                                         Aliphatics                                                                    Aromatics        42.0 18.9  43.5 32.7                                         Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                                 48.5   76.9    68.9 73.7                                   ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

Reference to the above results shows that the catalyst 9 treated withzinc fluoride affords a high aromatics yield and has a long life ascompared with the zinc-impregnated catalyst 8.

EXAMPLE 8

A transition metal silicate having an SiO₂ /Al₂ O₃ mol ratio of 50 andcontaining 0.3 wt. % of Fe₂ O₃ was subjected to a hydrothermalsynthesis, calcined at 550° C. for 5 hours, then treated with 1Nhydrochloric acid at 90°-100° C. for 5 hours, then washed with waterthoroughly and thereafter dried at 120° C. for 5 hours to obtain adealkalized, iron-containing transition metal silicate (catalyst 16)having a ZSM-5 type crystal structure.

Then, the catalyst 16 was impregnated with each of 3 wt. % Ag, Cr, Se,Re, Ni and Sn by an impregnation method to obtain catalysts 17, 18, 19,20, 21 and 22.

On the other hand, 4 wt. % AgF, 6 wt. % CrF₃, 5 wt. % SeOF₂, 5 wt. %ReF₆, 5 wt. % NiF₂ and 4 wt. % SnF₂ were each added and mixed to thecatalyst 16, and the resultant mixtures were compression-milded into 3×4mm dia. pellets, which were then calcined at 500° C. for 8 hours toobtain catalysts 23, 24, 25, 26, 27 and 28.

Using 2.0 g. of each of the twelve catalysts thus obtained, a life testwas made under the conditions of temperature 450° C., hydrogen flow rateof 4.2 l/hr, starting propylene gas feed rate 2.0 g/hr, hence hydrogento feed gas mol ratio ≈4, WHSV=1 hr⁻¹, at atmospheric pressure. Resultsare as set forth in Table 8.

Reference to Table 8 shows that the catalysts 23, 24, 25, 26, 27 and 28which have been heat-treated after support off the metal fluoridesafford high aromatics yields and have a long life.

                                      TABLE 8                                     __________________________________________________________________________    Catalyst      17     18     19     20     21     22                           __________________________________________________________________________    Support Metal Ag     Cr     Se     Re     Ni     Sn                           Run Time (hr) 10.0                                                                             200.0                                                                             10.0                                                                             200.0                                                                             10.0                                                                             200.0                                                                             10.0                                                                             200.0                                                                             10.0                                                                             200.0                                                                             10.0                                                                             200.0                     Conversion (%)                                                                              93.7                                                                             58.1                                                                              91.5                                                                             56.2                                                                              94.4                                                                             59.6                                                                              93.8                                                                             57.9                                                                              94.9                                                                             5917                                                                              92.6                                                                             57.3                      Distribution                                                                          C.sub.5.sup.+                                                                       44.4                                                                             23.0                                                                              43.5                                                                             22.9                                                                              8.4                                                                              10.2                                                                              45.2                                                                             23.7                                                                              50.0                                                                             26.9                                                                              46.2                                                                             23.6                      of Resulting                                                                          Aliphatics                                                            Hydrocarbons                                                                          Aromatics                                                                           13.4                                                                             6.1 12.3                                                                             5.5 40.1                                                                             14.5                                                                              13.9                                                                             5.9 12.3                                                                             5.8 12.5                                                                             5.3                       (wt. %)                                                                       C.sub.5.sup.+ 57.8oline* (wt. %)                                                               29.1                                                                              55.8                                                                             28.4                                                                              48.5                                                                             24.7                                                                              59.1                                                                             29.6                                                                              62.3                                                                             32.7                                                                              58.7                                                                             28.9                      __________________________________________________________________________    Catalyst      23     24     25     26     27     28                           __________________________________________________________________________    Support Metal AgF    CrF.sub.3                                                                            SeOF.sub.2                                                                           ReF.sub.6                                                                            NiF.sub.2                                                                            SnF.sub.2                    Run Time (hr) 10.0                                                                             200.0                                                                             10.0                                                                             200.0                                                                             10.0                                                                             200.0                                                                             10.0                                                                             200.0                                                                             10.0                                                                             200.0                                                                             10.0                                                                             200.0                     Conversion (%)                                                                              89.3                                                                             69.7                                                                              87.6                                                                             68.7                                                                              89.1                                                                             70.5                                                                              89.7                                                                             69.6                                                                              90.5                                                                             70.6                                                                              90.1                                                                             70.2                      Distribution                                                                          C.sub.5.spsb.+                                                                      43.0                                                                             32.5                                                                              42.1                                                                             32.2                                                                              7.0                                                                              7.3 44.0                                                                             34.2                                                                              49.5                                                                             39.8                                                                              44.6                                                                             33.3                      of Resulting                                                                          Aliphatics                                                            Hydrocarbons                                                                          Aromatics                                                                           15.9                                                                             11.6                                                                              15.0                                                                             10.9                                                                              44.3                                                                             37.7                                                                              15.5                                                                             11.3                                                                              15.2                                                                             11.0                                                                              14.7                                                                             10.5                      (wt. %)                                                                       C.sub.5.sup.+ 58.9oline* (wt. %)                                                               44.1                                                                              57.1                                                                             43.1                                                                              51.3                                                                             45.0                                                                              59.5                                                                             45.5                                                                              64.7                                                                             50.8                                                                              59.3                                                                             43.8                      __________________________________________________________________________     *C.sub.5.sup.+  aliphatics + aromatics                                   

EXAMPLE 9

Sodium form of ZSM-5 having an SiO₂ /Al₂ O₃ ratio of 78 was calcined at500° C. for 5 hours, then treated with 2N hydrochloric acid at 90°-100°C. for 5 hours, then washed with water thoroughly and thereafter driedat 120° C. for 5 hours to obtain a dealkalized ZSM-5. Then, the zeolitewas immersed in 3 mol/l of an aqueous ZnCl₂ solution at 70° C. for 1hour to obtain a dealkalized 2 wt. % Zn-supported ZSM-5 (catalyst 29).

Then, 20 wt. % of aluminum fluoride was added and mixed to the catalyst29 and the resultant mixture was formed into 3×4 mm dia. pellets, bycompression molding, which were then calcined at 500° C. for 8 hours(catalyst 30).

Using 2.0 g. of each of the catalysts thus obtained, life was evaluatedunder the conditions of temperature 300° C., hydrogen flow rate 2.0l/hr, feed butane-butene gas flow rate 2.0 g/hr, hence hydrogen to feedgas mol ratio 5, WHSV=1 hr⁻¹, at atmospheric pressure. Results are asset forth in Table 9 below.

                  TABLE 9                                                         ______________________________________                                                        Feed   Catalyst 29                                                                              Catalyst 30                                 Catalyst        Gas    (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      10.0   250.0   10.0 250.0                                  C.sub.4 + C.sub.4.sup.-  Conversion (%)                                                          83.7   39.9    77.7 63.2                                   Distribution                                                                            C.sub.1 -C.sub.2                                                                        --     19.2 6.1   16.1 11.0                               of Resulting                                                                            C.sub.3   3.1    16.6 3.3   9.6  9.2                                Hydrocarbons                                                                            C.sub.3.sup.-                                                                           1.4    3.3  16.4  5.4  8.0                                (wt. %)   C.sub.4   57.1   13.5 46.7  18.1 30.8                                         C.sub.4.sup.-                                                                           38.3   2.4  10.6  3.2  4.3                                          C.sub.5.sup.+                                                                           0.1    0.6  5.8   1.3  3.1                                          Aliphatics                                                                    Aromatics --     44.4 11.1  46.3 33.6                                         Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                              0.1    45.0   16.9  47.6 36.7                                 ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

From the above results it is seen that the catalyst 30 treated withaluminum fluoride affords high C₅ ⁺ gasoline yield and aromatics yieldand has a long life.

EXAMPLE 10

Sodium form of ZSM-5 having an SiO₂ /Al₂ O₃ ratio of 30 was calcined at500° C. for 5 hours, then treated with 2N hydrochloric acid at 90°-100°C. for 5 hours, then washed with water thoroughly and thereafter driedat 120° C. for 5 hours to obtain a dealkalized ZSM-5.

The dealkalized ZSM-5 was immersed in 2 mol/l of an aqueous GaCl₃solution, at 70° C. for 1 hour to obtain a dealkalized 2 wt. %Ga-supported ZSM-5 (catalyst 31).

Then, 20 wt. % of aluminum trifluoride was added and mixed to the abovecatalyst 31 and the resultant mixture was compression-molded into 3×4 mmdia. pellets, which were calcined at 500° C. for 8 hours (catalyst 32).

Using 2.0 g. of each of the thus-obtained catalysts, life was evaluatedunder the conditions of temperature 550° C., hydrogen flow rate 4.2l/hr, feed butane-butene gas flow rate 2.0 g/hr, hence hydrogen to feedgas mol ratio 5.0, WHSV=1 hr⁻¹, at atmospheric pressure. Results are asset forth in Table 10 below.

                  TABLE 10                                                        ______________________________________                                                        Feed   Catalyst 31                                                                              Catalyst 32                                 Catalyst        Gas    (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      10.0   250.0   10.0 250.0                                  C.sub.4 + C.sub.4.sup.-  Conversion (%)                                                          92.1   37.9    85.5 60.0                                   Distribution                                                                            C.sub.1 -C.sub.2                                                                        0.0    20.0 8.4   16.7 12.7                               of Resulting                                                                            C.sub.3   3.1    17.4 7.2   14.3 11.0                               Hydrocarbons                                                                            C.sub.3.sup.-                                                                           1.4    3.3  1.5   3.1  2.0                                (wt. %)   C.sub.4   57.1   6.4  48.7  10.3 33.4                                         C.sub.4.sup.-                                                                           38.3   1.1  10.5  2.5  4.7                                          C.sub.5.sup.+                                                                           0.1    0.5  0.2   0.5  0.4                                          Aliphatics                                                                    Aromatics 0.0    51.3 23.5  52.7 35.7                                         Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                              0.1    51.8   23.7  53.2 36.1                                 ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

From the above results it is seen that the catalyst 32 treated withaluminum trifluoride affords high C₅ ⁺ gasoline yield and aromaticsyield and has a long life.

EXAMPLE 11

Sodium form of ZSM-5 having an SiO₂ /Al₂ O₃ ratio of 50 was calcined at500° C. for 5 hours, then treated with 2N hydrochloric acid at 90°-100°C. for 5 hours, then washed with water thoroughly and thereafter driedat 120° C. for 5 hours to obtain a dealkalized ZSM-5.

The dealkalized ZSM-5 was immersed in 3 mol/l of an aqueous CdCl₂solution, at 70° C. for 1 hour to obtain a dealkalized 3 wt. %Cd-supported ZSM-5 (catalyst 33).

Then, 20 wt. % of ammonium fluoride was added and mixed to catalyst 33and the resultant mixture was compression-molded into 3×4 mm dia.pellets, which were then calcined at 500° C. for 8 hours (catalyst 34).

Using 2.0 g. of each of the catalysts thus obtained, life was evaluatedunder the conditions of temperature 600° C., hydrogen flow rate 4.2l/hr, feed butane gas flow rate 2.0 g/hr, hence hydrogen to feed gas molratio 5, WHSV=1 hr⁻¹, at atmospheric pressure. Results are as set forthin Table 11 below.

                  TABLE 11                                                        ______________________________________                                                        Feed    Catalyst 33                                                                              Catalyst 34                                Catalyst        Butane  (Comp. Ex.)                                                                              (Example)                                  ______________________________________                                        Run Time (hr)       1.0    50.0    1.0  50.0                                  Conversion (%)      50.2   22.6    48.8 39.7                                  Distribution                                                                            C.sub.1 -C.sub.2  14.8 5.6   11.6 6.1                               of Resulting                                                                            C.sub.3           8.8  3.3   7.3  6.8                               Hydrocarbons                                                                            C.sub.4   100.0   48.8 77.4  51.2 60.3                              (wt. %)   C.sub.5.sup.+     0.3  0.2   0.5  0.8                                         Aliphatics                                                                    Aromatics         27.3 13.5  29.4 26.0                                        Total     100.0   100.0                                                                              100.0 100.0                                                                              100.0                             C.sub.5.sup.+  Gasoline* (wt. %)                                                                  27.6   13.7    29.9 26.8                                  ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

Reference to the above results shows that the catalyst 34 treated withammonium fluoride affords high C₅ ⁺ gasoline yield and aromatics yieldand has a long life.

EXAMPLE 12

Using the same catalysts 29 and 30 as in Example 9, catalyst life in anaromatization reaction of n-hexane was evaluated under the conditions oftemperature 500° C., hydrogen flow rate 3.6 l/hr, feed rate 2.0 g/hr,WHSV=1 hr⁻¹, at atmospheric pressure. Results are as set forth in Table12 below.

                  TABLE 12                                                        ______________________________________                                                        Feed   Catalyst 29                                                                              Catalyst 30                                 Catalyst        n-C.sub.6                                                                            (Comp. Ex.)                                                                              (Example)                                   ______________________________________                                        Run Time (hr)      10.0   200.0   10.0 200.0                                  Conversion (%)     100.0  68.4    92.3 75.1                                   Distribution                                                                            C.sub.1 -C.sub.2 24.1 4.1   12.1 9.8                                of Resulting                                                                            C.sub.3          23.7 11.5  15.6 12.6                               Hydrocarbons                                                                            C.sub.4          2.6  10.4  6.9  5.6                                (wt. %)   C.sub.5.sup.+                                                                           100.0  0.8  52.7  23.1 37.3                                         Aliphatics                                                                    Aromatics        48.8 21.3  42.3 34.7                                         Total     100.0  100.0                                                                              100.0 100.0                                                                              100.0                              C.sub.5.sup.+  Gasoline* (wt. %)                                                                 49.6   74.0    65.4 72.0                                   ______________________________________                                         *C.sub.5.sup.+  aliphatics + aromatics                                   

Reference to the above results shows that the catalyst 30 treated withaluminum fluoride has a long life.

EXAMPLE 13

A transition metal silicate having an SiO₂ /Al₂ O₃ mol ratio of 90 andcontaining 0.5 wt. % of Fe₂ O₃ was subjected to a hydrothermalsynthesis, calcined at 500° C. for 5 hours, then treated with 1Nhydrochloric acid at 90°-100° C. for 5 hours, then washed with waterthoroughly and thereafter dried at 120° C. for 5 hours to obtain adealkalized, iron-containing transition metal silicate having a ZSM-5type crystal structure.

Then, the silicate was impregnated with each of 3 wt. % Cu, Cr, Te, Reand Ni by an impregnation method to obtain catalysts 35, 36, 37, 38 and39.

Then, 20 wt. % Aluminum trifluoride was added and mixed to each of thefive catalysts, and the resultant mixtures were compression-molded into3×4 mm dia. pellets, which were then calcined at 500° C. for 8 hours toobtain catalysts 40, 41, 42, 43 and 44.

Using 2.0 g. of each of the ten catalysts thus obtained, a life test wasmade under the conditions of temperature 480° C., hydrogen flow rate of4.2 l/hr, starting propylene gas feed rate 2.0 g/hr, hence hydrogen tofeed gas mol ratio ≈4, WHSV=1 hr⁻¹, at atmospheric pressure. Results areas set forth in Table 13.

                                      TABLE 13                                    __________________________________________________________________________    Catalyst      35     36     37     38     39                                  __________________________________________________________________________    Support Metal Cu     Cr     Te     Re     Ni                                  AlF.sub.3 treatment                                                                         none   none   none   none   none                                Run Time (hr)  5.0                                                                             150.0                                                                              5.0                                                                             150.0                                                                              5.0                                                                             150.0                                                                              5.0                                                                             150.0                                                                              5.0                                                                             150.0                            Conversion (%)                                                                              94.3                                                                             59.5                                                                              92.5                                                                             57.1                                                                              95.2                                                                             60.0                                                                              94.7                                                                             59.8                                                                              95.5                                                                             60.5                             Distribution                                                                          C.sub.5.sup.+                                                                       41.3                                                                             21.5                                                                              40.1                                                                             21.1                                                                              4.8                                                                              8.3 42.6                                                                             21.3                                                                              45.7                                                                             24.8                             of Resulting                                                                          Aliphatics                                                            Hydrocarbons                                                                          Aromatics                                                                           15.5                                                                              7.0                                                                              14.7                                                                              6.6                                                                              43.5                                                                             15.7                                                                              15.2                                                                              6.8                                                                              14.8                                                                              6.7                             (wt. %)                                                                       C.sub.5.sup.+ 56.8oline* (wt. %)                                                               28.5                                                                              54.8                                                                             27.7                                                                              48.3                                                                             24.0                                                                              57.8                                                                             28.1                                                                              60.5                                                                             31.5                             __________________________________________________________________________    Catalyst      40     41     42     43     44                                  __________________________________________________________________________    Support Metal Cu     Cr     Te     Re     Ni                                  Alf.sub.3 treatment                                                                         treated                                                                              treated                                                                              treated                                                                              treated                                                                              treated                             Run Time (hr)  5.0                                                                             150.0                                                                              5.0                                                                             150.0                                                                              5.0                                                                             150.0                                                                              5.0                                                                             150.0                                                                              5.0                                                                              150.0                           Conversion (%)                                                                              9.13                                                                             71.5                                                                              89.6                                                                             70.2                                                                              91.1                                                                             72.1                                                                              91.7                                                                             71.8                                                                              92.5                                                                             72.4                             Distribution                                                                          C.sub.5.sup.+                                                                       41.5                                                                             34.0                                                                              41.2                                                                             34.3                                                                               5.5                                                                              7.8                                                                              42.2                                                                             35.4                                                                              47.8                                                                             40.5                             of Resulting                                                                          Aliphatics                                                            Hydrocarbons                                                                          Aromatics                                                                           16.2                                                                             12.2                                                                              15.3                                                                             11.5                                                                              45.2                                                                             39.7                                                                              15.8                                                                             11.9                                                                              15.5                                                                             11.6                             (wt. %)                                                                       C.sub.5.sup.+ Gasoline* (wt. %)                                                             57.7                                                                             46.2                                                                              56.5                                                                             45.8                                                                              50.7                                                                             47.5                                                                              58.0                                                                             47.3                                                                              63.3                                                                             52.1                             __________________________________________________________________________     *C.sub.5.sup.+ aliphatics + aromatics                                    

Reference to Table 13 shows that the catalysts 40, 41, 42, 43 and 44which have been treated with aluminum fluoride afford high aromaticsyields and have a long life.

EXAMPLE 14

ZSM-5 having an SiO₂ /Al₂ O₃ mol ratio of 45 was prepared by ahydrothermal synthesis, calcined at 500° C. for 5 hours, then treatedwith 2N hydrochloric acid at 90°-100° C. for 5 hours, then washed withwater thoroughly and thereafter dried at 120° C. for 5 hours to obtain adealkalized ZSM-5. Subsequently, 3 wt. % of Zn was supported thereon byan impregnation method and further supported 0.5 wt. % Pt by an ionexchange method to obtain catalyst 45.

15 wt. % of ammonium fluoride was added and mixed to the catalyst 45 andthe resultant mixture was compression-molded into 3×4 mm dia. pellets,which were then calcined at 500° C. for 8 hours to obtain catalyst 46.

Using 2.0 g. of each of the catalysts thus obtained, a life test in areformate aromatization reaction was made under the conditions oftemperature 490° C., hydrogen flow rate of 5.0 l/hr, feed rate 2.0 g/hr,WHSV=1 hr⁻¹, at atmospheric pressure. Results are as set forth in Table14.

                  TABLE 14                                                        ______________________________________                                                        Feed                                                                          Refor-  Catalyst 45                                                                              Catalyst 46                                Catalyst        mate    (Comp. Ex.)                                                                              (Example)                                  ______________________________________                                        Run Time (hr)   --      10.0   500.0 10.0 500.0                               C.sub.5.sup.+  Aliphatics                                                                     --      95.2   28.6  89.8 62.9                                Conversion (%)  (%)                                                           Distribution                                                                            C.sub.1   1.6     7.3  5.0   6.8  7.1                               of Resulting                                                                            C.sub.2 -C.sub.4                                                                        15.3    26.8 18.9  23.9 18.7                              Hydrocarbons                                                                            C.sub.5.sup.+                                                                           35.3    1.7  25.2  3.6  13.1                              (wt. %)   Aliphatics                                                                    Aromatics 47.8    64.2 50.9  65.7 61.1                                        Total     100.0   100.0                                                                              100.0 100.0                                                                              100.0                             C.sub.5.sup.+  Gasoline* (wt. %)                                                              83.1    65.9   76.1  69.3 74.2                                ______________________________________                                         C.sub.5.sup.+  aliphatics + aromatics                                    

Reference to Table 14 shows that the catalyst 46 treated with ammoniumfluoride affords a high aromatics yield and has a long life.

What is claimed is:
 1. A process for converting hydrocarbons to aromatichydrocarbons or gasoline having a high octane number, characterized bycontacting a feed stock containing at least one aliphatic hydrocarbonhaving 1 to 12 carbon atoms with a catalyst at an elevated temperature,said catalyst comprising a dealkalized zeolite obtained from a zeolitehaving a SiO₂ /Al₂ O₃ mol ratio in the range 1 to 90 and a solidfluorine compound selected from the group consisting of aluminumfluoride, ammonium fluoride, magnesium fluoride, barium fluoride,zirconium fluoride, zinc fluoride, gallium fluoride, cadmium fluoride,nickel fluoride, chromium fluoride, tin fluoride, copper fluoride,silver fluoride, rhenium fluoride, manganese fluoride, molybdenumfluoride, selenium fluoride, tellurium fluoride, tungsten fluoride,lanthanum fluoride, cerium fluoride, titanium fluoride and calciumfluoride.
 2. A process as set forth in claim 1, wherein said fluorinecompound is aluminum fluoride, ammonium fluoride, magnesium fluoride orzirconium fluoride.
 3. A process as set forth in claim 1, wherein saidfeed stock comprises one or more aliphatic hydrocarbons having 2 to 4carbon atoms.
 4. A process as set forth in claim 1, wherein said feedstock is a light straight-run naphtha distillate.
 5. A process as setforth in claim 1, wherein said feed stock is a reformed naphthadistillate.
 6. A process as set forth in claim 1, wherein said feedstock is a thermal-cracked gasoline.
 7. A process as set forth in claim1, wherein said contact reaction is carried out in the presence ofhydrogen.
 8. A process as set forth in claim 1, wherein said catalystfurther contains at least one member selected from Group Ib, IIb, IIIa,VI, VIIb and VIII metals in the Periodic Table and said conversion is anaromatization reaction.
 9. A process as set forth in claim 8, whereinsaid fluorine compound is aluminum fluoride, ammonium fluoride,magnesium fluoride or zirconium fluoride.
 10. A process as set forth inclaim 8, wherein said metal is at least one member selected from Cu, Ag,Zn, Cd, Ga, Cr, W, Se, Te, Re, Co, Ni, Pd, Ir and Pt.
 11. A process asset forth in claim 8, wherein said feed stock comprises one or morealiphatic hydrocarbons having 2 to 4 carbon atoms.
 12. A process as setforth in claim 8, wherein said feed stock is a light straight-runnaphtha distillate.
 13. A process as set forth in claim 8, wherein saidfeed stock is a reformed naphtha distillate.
 14. A process as set forthin claim 8, wherein said feed stock is a thermal-cracked gasoline.
 15. Aprocess as set forth in claim 8, wherein said contact reaction iscarried out in the presence of hydrogen.
 16. A process as set forth inclaim 1, wherein said catalyst is that obtained by dealkalizing azeolite having a SiO₂ /Al₂ O₃ mol ratio in the range of 1 to 90,contacting the dealkalized zeolite with the fluorine compound andcalcining the mixture thus obtained.